Step-wise reduction kinetics of Fe 2 O 3 by CO/CO 2 mixtures for chemical looping hydrogen generation
| Autor: | Yingdi Wang, Wei Li, Wenrui Wang, Tiantian Fu, C.C. Zhao, Xiuning Hua |
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| Rok vydání: | 2017 |
| Předmět: |
Arrhenius equation
Reaction mechanism Renewable Energy Sustainability and the Environment Chemistry 05 social sciences Nucleation Energy Engineering and Power Technology Thermodynamics 02 engineering and technology Activation energy Rate equation 021001 nanoscience & nanotechnology Condensed Matter Physics Reaction rate symbols.namesake Fuel Technology 0502 economics and business symbols Physical chemistry 050207 economics 0210 nano-technology Chemical looping combustion Hydrogen production |
| Zdroj: | International Journal of Hydrogen Energy. 42:5667-5675 |
| ISSN: | 0360-3199 |
| DOI: | 10.1016/j.ijhydene.2017.01.159 |
| Popis: | The reduction kinetics of iron-based oxygen carriers significantly affect the efficiency of chemical looping hydrogen generation. Based on the thermodynamics properties of the Fe–CO–CO 2 system, CO/CO 2 mixtures in different volume ratios can decouple the reduction of Fe 2 O 3 into three relatively independent steps. The step-wise reduction of Fe 2 O 3 was conducted in a thermogravimetric analyzer at 800–900 °C. To investigate the reaction mechanisms, the Hancock–Sharp method and the nonlinear fitting approach were applied to select the kinetic models. The reaction model of step 1 and 2 are geometrical contracting model; the step 3 is controlled by nucleation and nuclei growth model and diffusion model. The activation energy of the three steps including Fe 2 O 3 → Fe 3 O 4 , Fe 3 O 4 → FeO and FeO → Fe is estimated to be 34.92 ± 1.24, 70.13 ± 0.88 and 44.12 ± 1.44 kJ/mol, respectively. The rate equations derived from the Arrhenius law were determined to predict the reaction rate at a specific CO concentration. |
| Databáze: | OpenAIRE |
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